Purpose or Case Report: Accurate preoperative imaging diagnosis of supratentorial pediatric intraventricular tumors is not always straightforward. Conventional MRI features such as T1- and T2-weighted signal and contrast enhancement may overlap among various choroid plexus tumors and embryonal tumors. This study aimed to perform apparent diffusion coefficient (ADC) histogram analysis, assessing various metrics in different intraventricular for histological classification.
Methods & Materials: Twenty-three intraventricular pediatric tumors were retrospectively evaluated. There were 12 choroid plexus papillomas (CPP), six choroid plexus carcinomas (CPC), three ATRTs, one PNET, and one medulloepithelioma. The ATRT, PNET, and medulloepithelioma cases were bundled in a single group of embryonal tumors according to the 2016 WHO classification of brain tumors. All tumors were investigated by MRI by using diffusion-weighted imaging. All tumors were manually segmented using an in-house developed parametric (pMRI) software and diffusivity metrics were automatically calculated on a pixel-by-pixel basis. Only the solid components of the lesions were included in the analysis. The following first-order histogram radiomic metrics were calculated: mean ADC_mean, ADC_Kurtosis, ADC_skewness, ADCv_ariance, and Shannon index of entropy. Differences in the whole tumor metrics were assessed using the Kruskal-Wallis test with post hoc comparison.
Results: There were significant differences in ADC_mean (1744±101 vs 1215±136 vs 971±150 10-3mm/s², p<0.002) ADC_Kurtosis (1.01±0.54 vs 2.191±0.739 vs 4.635±0.809, p<0.022) among choroid plexus papilloma, choroid plexus carcinoma, and intraventricular embryonal tumors, respectively. In post hoc analysis, the ADC_mean of CPP was significantly higher than CPC and embryonal tumors, and on the other hand, the ADC_kurtosis of embryonal tumors was significantly higher from both types of choroid plexus tumors.
Conclusions: Embryonal tumors had significantly lower ADC_mean values as compared with choroid plexus tumors. CPC had significantly lower ADC_mean values as compared with CPP. ADC histograms of embryonal tumors were significantly more leptokurtic than choroid plexus tumors. ADC histograms of CPPs were significantly more platykurtic than CPPs. ADC_mean of the whole tumor and the shape of the ADC histograms may be useful metrics for the preoperative histological diagnosis of pediatric supratentorial tumors.